The invention is related to soil conditioning agents. Particularly, the invention relates to cellulose fiber based soil conditioning agents, particularly those which are regarded as highly effective in promoting aggregate formation, reducing soil erosion, and improving water utilization within agricultural soil. More particularly, the invention utilizes lignocellulosic fibers containing a soil conditioning agent or agents.
The effectiveness and efficiency of modern day agriculture is determined by the ability to fully utilize nutrients within the soil and the ability to maintain those nutrients within the soil over the life of a growing plant. To maintain nutrient levels within the soil, various soil conditioners are often added to the soil. The soil conditioners attempt to meet the demands of high-efficiency agriculture. Soil conditioners are also increasingly used in personal horticulture and landscaping.
The role of soil conditioners is several-fold. The conditioners must support seed germination, encourage seedling emergence, provide the efficient use of water, and prevent erosion. The most important aspect of the conditioner is the ability to increase aggregate formation (e.g., in sandy soils) which promotes water retention. Effective control of soil water controls erosion and prevents soil crusting. Erosion is controlled by encouraging absorption of water within the soil and prevention of free-flowing water over the soil surface. Soil crusting is a situation caused by the disintegration of the top layers of soil and formation of a powder-like surface layer with relatively little porosity which prevents water from penetrating through the top layer of soil. Crusting is abated by equalizing the moisture content of the soil. Water retention is aided by the addition of hydrophilic conditioning elements which hold water within the top several layers of soil and prevent the water from rapidly leaching through the soil.
One of the most effective methods of soil conditioning involves dispersing synthetic organic polymers into or onto the soil. Classes of polymers such as high molecular weight polyacrylamides, poly(ethylene glycol), poly(vinyl alcohol), copolymers of maleic anhydride, and poly(urea formaldehyde) are useful as soil conditioners. Superabsorbent polymers that are extremely hydrophilic and have the ability to absorb several times their own weight in water are also useful in improving water retention in soils. The superabsorbent polymers do not move easily through the soil, so water contained within the polymer is not allowed to leach through the soil. Rather, the water is retained, and is available to crops. As the soil dries, water is released from the polymer and also becomes available to the crops. Thus, the polymer acts as a buffer which equalizes the release of water within the soil.
Water soluble, anionic high molecular weight polyacrylamides (PAMs) are particularly useful polymeric soil conditioners in improving aggregate formation, reducing soil erosion and promoting water retention. The polymers are typically dissolved within irrigation water and applied to the soil being conditioned. They have been extensively studied by the EPA and other regulatory agencies and appear to have minimal toxicity and environmental effects.
Water insoluble but water swellable PAM superabsorbents can be produced by introduction of a significant degree of cross-linking into anionic PAMs (e.g., with methylenebisacrylamide). They are known to be quite hydrophilic with the ability to absorb 500 times their weight in water. These water retention properties have led to the utilization of PAM superabsorbents in soil system applications in horticulture, turf culture, seed coating, hydromulching and transplanting.
However, there are problems related to the use of soil conditioning polymers, such as the “PAMs”. First, the anionic PAM soil conditioners are typically applied by dispersing the polymers within irrigation water. If a portion of the irrigation water flows over the soil and does not properly penetrate the soil, then the polymers within the water will likewise not be absorbed into the soil. Also, since the polymers follow the flow of irrigation water, which may or may not be uniform, the polymers are typically not well distributed within the soil. Thus, large quantities of the relatively expensive polymer may be required for proper efficacy. With regard to hydrophilic superabsorbent polymers (e.g., cross-linked anionic PAM), the superabsorbent polymers can gel together when placed on or within the soil. The gelled polymers clog the porous soil and may prevent water from penetrating the soil. Thus, improper application or use of superabsorbent polymers may be counterproductive as well.
It is desired to apply soil conditioning polymers to soil so that previously encountered problems with synthetic organic polymers may be avoided while reducing erosion and providing improved soil water control. It is desired to apply soil conditioners and superabsorbent polymers to soil such that they are well distributed throughout the targeted area of soil and readily permeate the soil without leaching through the soil.